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Pulp Paper & Logistics


High-alloy steels improve recovery boiler reliability

of a recovery boiler used in a eucalyptus pulp mill in Uruguay to reduce the costs of maintenance and replacements experienced with conventional steel tubing. The carbon steel tubing used in the superheater panels had been suffering from the effects of the chloride used in the bleaching process. Accumulations of the


omposite steel tubing supplied by Sandvik has been installed in the superheaters

chemical, in conjunction with high temperatures, were having a detrimental effect on the existing steel tubes. Despite the installation of a chloride removal system, the chemical is still a vital part of the overall process and it therefore cannot be completely eradicated. Depending on the size of

recovery boiler the production losses could be as high as $1.5 million per day. In addition to the amount of tube replacements that were needed on a regular basis, the issues of

increased production downtime, inspection and maintenance required were also major areas of concern. Andritz was invited to undertake a evaluation of the original superheater equipment, and replacement of the tubing with Sandvik Sanicro 28 – a high-alloy, multi-purpose austenitic stainless steel, developed for use in highly- corrosive conditions – was recommended. Timo Peltola, product manager for composite and boiler tubes

at Sandvik Materials Technology, said: “This is an excellent example of how selecting quality composite tubes will provide a reliable solution for customers when compared to some of the cheaper, inferior products on the market.” A year after the installation, Andritz reports that there are no defects or corrosion damage found in the composite tubes. More information from Sandvik Materials Technology, SE-811 81 Sandviken, Sweden.

May/June 2015

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